Draw the menu shadows on viewDidAppear instead of viewDidLoad. This is necessary because when the iPad is launched in landscape, the centerViewController reports a portrait frame until viewDidAppear.

[#97]
Always set the right menu to the right side of the menuContainerView.

[Fixes #97]
Don't set side menu frames until the views have appeared [Fixes #105]
Improve support for rotations in iOS 6 [#85]